What we don't know is what Putin's intentions really are

Foreign Secretary William Hague has called in the Russian Ambassador to ask for an explanation, he's also asked for and got a meeting of the UN Security Council tonight. But Russia wields a veto on that body and it's not at all clear what they can do about it.

Does he really intend a shooting war with Ukraine? Is he gambling that Ukrainians simply won't fight? Or is he simply raising the tension so high now that when he backs down and doesn't invade the world breathes a sigh of relief and accepts his conquest of Crimea.